Making decisions efficiently is the process of weighing costs and benefits. And while enormous progress has been made in the last two decades towards understanding the neural mechanisms by which humans and monkeys weigh benefits, much less is known about how the brains of these species weigh costs. There is, however, growing evidence from both humans and monkeys indicating that costs and benefits may be encoded by distinct neural systems and integrated quite late in the decision cascade. Here we propose a set of simple experiments designed to orthogonalize costs and benefits during human and monkey decision-making while we measure - and manipulate - neural activity in a suite of decision-related areas. Our goal is to test the hypothesis that separate anterior areas (mostly in the frontal cortex) maintain separate representations of costs and benefits, representations that are subsequently integrated for choice (in oculomotor tasks) in what are often called the fronto-parietal choice circuits. To test this hypothesis we propose a complementary set of functional Magnetic Resonance Imaging (fMRI) experiments in humans and single unit recording and muscimol inactivation experiments in monkeys. The fMRI experiments allow for a large-scale whole-brain test of our hypothesis. The single unit studies allow a rigorous quantitative measurement of the degree of cost and benefit representation in each area and the ability to establish a causal for some or all of these areas in cost benefit integration.